DH Instruments PPC4, Руководство по эксплуатации и обслуживанию

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7. MAINTENANCE, ADJUSTMENTS AND CALIBRATION
Page 187 © 2009 DH Instruments, a Fluke Company
Prior to running the calibration point sequence, the Q-RPT should be exercised by:
a) Setting full scale pressure.
b) Dwelling at full scale pressure for 5 minutes.
c) Returning to atmospheric pressure (vented). If the Q-RPT is a gas operated Axxx type,
use vacuum rather than atmospheric pressure.
d) Dwelling for twenty minutes.
A dwell time after setting the pressure of at least 60 seconds before taking data at each point
is recommended.
Section 7.2.4.1 gives calibration point sequences for Standard and Full Scale Standard Class
Q-RPTs and Section 7.2.4.2 gives calibration point sequences for Premium Q-RPTs.
Note
It is not required that the calibration pressure standard apply precisely the
nominal pressure value of each calibration point as long as the exact value
of the applied pressure is known. Best results are obtained if the actual
applied pressure is within 2 % of the nominal point definition.
7.2.4.1 Standard and Full Scale Standard Class Q-RPTs
See additional information in Section 7.2.4 concerning exercising the Q-RPT and
dwell time at pressure points.
Table 27. Calibration Point Sequence, Standard Class, Axxx and Gxxx Q-RPTs
CALIBRATION
SEGMENT
POINT
NO.
POINT
[% OF SPAN]
Ascending
1 Lowest Pressure
1
2 25 %
3 50 %
4 75 %
5 100 %
Descending
6 75 %
7 50 %
8 25 %
9 Lowest Pressure
1
1 In absolute mode, the lowest point that can be set reliably by
the reference piston gauge. Zero (vented) in gauge mode.
Note
Axxx (absolute) Q-RPTs that will NOT be used in absolute or
negative gauge measurement modes may be calibrated in gauge
measurement mode with a gauge pressure standard. Axxx
(absolute) Q-RPTs calibrated in gauge measurement mode by
applying gauge reference pressure values should be used in
gauge mode only (see Section 7.2.5).